Cubescript is the core language for FPS mode. RPG, however, has a name that Hirato came up with and I can't actually remember the name of it. However, if you check the related Wiki for RPG Scripting, I'm sure you'll find some useful information.

Hope this helps, Leo.PS. Your English isn't as bad as you think.PSS. Lamiea is the name of the refined RPG module derived from the Sandbox Core that Hirato was working on whilst I was still working on the project. Wind Astella mentioned it in a forum post, so credit goes to her for jogging my memory on that subject.